What Is FIX Protocol? — TraderEvolution

FIX (Financial Information eXchange) is a messaging standard used by financial institutions to communicate trading information electronically. Developed in 1992 by Salomon Brothers and Fidelity Investments, FIX has become the dominant protocol for order routing, execution reporting, and market data distribution across equities, fixed income, derivatives, and foreign exchange markets.

For brokers, FIX is how you connect to institutional liquidity providers, exchanges, and professional clients. Understanding FIX is essential for anyone operating or evaluating multi-asset trading infrastructure.

How FIX works

FIX is a session-based protocol. Two systems establish a FIX session (a persistent connection), then exchange messages using a standardised format. Each message has a type (new order, execution report, market data snapshot) and a set of fields (tags) that carry the data.

Key message types: New Order Single (tag 35=D), Execution Report (35=8), Order Cancel Request (35=F), Market Data Request (35=V), and Market Data Snapshot (35=W). These cover the core of order lifecycle management.

Tag-value format: FIX messages are structured as tag=value pairs separated by delimiters. For example: 35=D|49=BROKER|56=LP|55=EUR/USD|54=1|38=100000|40=2|44=1.0950 — a limit buy order for 100,000 EUR/USD at 1.0950.

FIX in the broker workflow

LP connectivity: Brokers use FIX to connect to liquidity providers. The order routing engine sends FIX messages to LPs and receives execution reports back. TraderEvolution's 80+ integrations include many FIX-based connections.

Institutional clients: Professional traders, hedge funds, and other brokers connect to your platform via FIX. They send orders from their OMS (Order Management System) directly to your back-end. TraderEvolution's FIX API supports inbound client connections.

Exchange connectivity: Some exchanges accept orders via FIX. The platform translates internal orders into FIX messages and routes them to the exchange for execution.

FIX vs other protocols

FIX is not the only option. Modern trading platforms support multiple connectivity protocols:

REST API: HTTP-based, request-response. Good for administrative operations, historical data, and integration with web services. TraderEvolution uses REST for the BackOffice API and parts of the Client API.

WebSocket: Full-duplex, real-time. Ideal for streaming market data and account events to front-ends. The Client API uses WebSocket for live data subscriptions.

MCP (Model Context Protocol): Structured tool access for AI agents. TraderEvolution's MCP Server provides 31 tools built on top of the Client API for AI-driven trading.

FAQ

Do brokers need FIX protocol support?

Yes, if they want to connect to institutional liquidity providers, exchanges, or serve professional clients who use FIX-based OMS systems. FIX is the standard protocol for institutional order flow. TraderEvolution includes FIX API support as part of the platform.

What FIX version does TraderEvolution support?

TraderEvolution supports FIX 4.4, which is the most widely used version in the retail and institutional brokerage space. The FIX API supports both inbound (receiving orders from FIX clients) and outbound (sending orders to FIX-based LPs and exchanges) connectivity.

Is FIX protocol the same as an API?

FIX is a specific protocol standard, while API is a general term for any programming interface. TraderEvolution provides multiple API types: FIX API for institutional connectivity, Client API (WebSocket + REST) for front-end integration, and BackOffice REST API for administrative operations. Each serves different use cases.

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What Is the FIX Protocol?